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Chapter 1
Introduction to
Computer
Operating System
Objectives
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When finish this chapter, you will
understand:
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what an operating system is.
a brief history of operating systems.
goals of operating systems.
operating system functions.
type of operating systems
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What is an Operating System (OS)?
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A program that acts as an intermediary between a
user of a computer and the computer hardware.
A set of programs that coordinates all activities
among computer hardware resources.
Operating system goals:
 Execute user programs and make solving user
problems easier.
 Make the computer system convenient to use.
 Use the computer hardware in an efficient manner.
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Operating System history
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Early History: The 1940s and 1950s
Operating systems evolved through several
phases
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1940s
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Early computers did not include operating systems
1950s
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Executed one job at a time
Included technologies to smooth job-to-job transitions
Single-stream batch-processing systems
Programs and data submitted consecutively on
tape
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1960s
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Still batch-processing systems
Process multiple jobs at once
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Multiprogramming
One job could use processor while other
jobs used peripheral devices
Advanced operating systems developed to
service multiple interactive users
1964
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IBM announced System/360 family of
computers
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The 1970s
Primarily multimode timesharing systems
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Supported batch processing, timesharing and realtime applications
Department of Defense develops TCP/IP
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Standard communications protocol
Widely used in military and university settings
Security problems
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Growing volumes of information passed over vulnerable
communications lines.
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1980s
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Decade of personal computers and workstations
Computing distributed to sites at which it was
needed
Personal computers proved relatively easy to learn
and use
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Graphical user interfaces (GUI)
Transferring information between computers via
networks became more economical and practical
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The 1980s (con’t)
Client/server computing model became
widespread
 Clients request various services
 Servers perform requested services
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The 1990s
Operating systems became increasingly user
friendly
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GUI features pioneered by Apple widely used and
improved
“Plug-and-play” capabilities built into operating
systems
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Enable users to add and remove hardware components
dynamically
No need to manually reconfigure operating system
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2000 and Beyond
Middleware
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Links two separate applications
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Particularly important for Web services
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Often over a network and between incompatible
machines
Simplifies communication across multiple architectures
Web services
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Encompass set of related standards
Ready-to-use pieces of software on the Internet
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What are the main functions of an
operating system?
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Start up the computer
Administrator security
Control network
Access the web
Monitor performance and provide housekeeping
services
Schedule jobs and configure devices
Manage memory
manage programs
Provide user interface
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Where is the operating system
located?
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Operating System resides on ROM chip
in handhelds devices like PDA, Mobile
Phone.
Operating System resides on hard disk
in most computer cases.
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Operating System Functions
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What is booting?
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a process of starting or restarting a computer.
Cold Boot
Warm boot
Process of turning on a
computer after it has been
powered off completely.
Process of restarting a
computer
that is already powered on.
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Operating System Functions
How does a personal computer booting up?
 Step 1
1-Power supply sends signal to components
in system unit
2-The processor accessed BIOS to start
computer
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Operating System Functions
What messages display when you boot the
computer?
BIOS version and copyright
notice
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total amount of memory
ROMBIOS Version 2.10 A05
Copyright notices
0065536KB
Keyboard .... Detected
devices detected and
tested
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Windows message
Mouse.....Detected
Hard Disk Installed WCW AC4160011
Floppy A: Installed
Starting Windows
SoundUTIL TSR Version 1.20
Sound card and
CD-ROM drivers loaded
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Copyright SoundCard Technology 2001
IDE CD-RW Device Driver Ver .2.3
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Operating System Functions
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Step 3
BIOS checks components such as
mouse, keyboard connectors and
expansion cards
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Operating System Functions
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Step 4
Results of POST are compared to data
in the CMOS chip
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Operating System Functions
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Step 5
BIOS looks for system files in drive A
(Floppy disk drive) and then drive C
(hard disk) and then...
Drive that contains operating system is
called boot drive.
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Operating System Functions
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Step 6
Boot program loads kernel of operating
system into RAM from boot drive
operating system in memory takes
control of computer
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Operating System Functions
Step 7
 operating system loads
configuration information and
displays desktop on screen
 operating system executes
programs in startup folder
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Operating System Functions
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What is a user interface?
controls how you enter data and instructions
and how information displays on screen.
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Operating System Functions
What is Multitasking?
 allows a single user
to work on two or more
applications that reside
in memory at same
time.
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Operating System Functions
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What are other program management features of OS?
Multiuser
Multiprocessing
Operating System enables
two or more
users to run a program
simultaneously
Operating System can
support two or
more processors running
programs at same time
Fault-Tolerant
Continues to operate even if
one of its components fails
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Operating System Functions
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What is Memory management?
Optimizes the use of random access memory
(RAM)
allocates or resigns, data and instructions to
area of memory while they are being processed
monitors contents of memory
clears items from memory when processor no
longer requires them
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Operating System Functions
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What is virtual memory (VM) management?
Operating system allocates portion of hard
disk to function like RAM
Paging
Page
File
Virtual Disk
RAM
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Operating System Functions
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How does an operating system schedule jobs?
Job
an operation the
processor manager
Transferring items
from storage to
memory
Receiving data
from
input devices
Sending
information to
an output devices
Processing
Instructions
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Operating System Functions
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What is spooling?
Print jobs sent to buffer instead of directly to printer,
where print jobs wait their turn
Print Queue
Print Job list
Disk
Jobs to
be
printed
Jobs being printed

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Operating System Functions
How does an operating system monitor
performance?
 Provides a program
called performance monitor,
that assesses and reports
information about various
system resources and
devices.
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Operating System Functions
How does an operating system manage files?
 Includes a program
called file manager,
such as Windows
Explorer.
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Commands
Copy, Rename,
Delete, move ...
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Operating System Functions
What is a file allocation table (FAT)?
 a table of information
that operating system
uses to locate file on
a disk.
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Operating System Functions
What are functions of operating system on
network?
 Establish network
connection
 Controlling network
traffic
 Closing network
connection
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Type of Operating System
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Desktop Operating System
a program control activities in standalone computer.
Such as MS-Windows 9X, MS-Windows NT
workstation
MS-Windows 2000 Professional, MS-Windows XP
Professional
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Network Operating System
a program control activities both on local computer
and other computer on network.
Such as MS-Windows NT Server, Windows 2000
Server, MS-Windows 2000 Advance Server, MSWindows 2003 Server
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Operating System Goals
Users expect certain properties of operating systems
 Efficiency
 Robustness
 Scalability
 Extensibility
 Portability
 Security
 Protection
 Interactivity
 Usability
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Operating System Architectures
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Today’s operating systems tend to be
complex
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Provide many services
Support variety of hardware and software
Operating system architectures help
manage this complexity
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Review Questions
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What are the main roles of operating
system?
How many type of operating system?
Explain some of operating system goal.
Homework
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Brief evolution of operating system
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